Selective User Notification Based on IP Flow Information

ABSTRACT

An example embodiment of the present invention provides a process that uses IP flow information to selectively notify users of an application server of the server&#39;s unavailability. In the example embodiment, the process, which might run on a system comprising a router, monitors IP flow records as to dropped packets and learns that an application server has become unavailable. The process then uses the IP flow records to identify active users of the application server, for example, by passing a source IP address to a presence service. Once the process has identified an active user, the process determines a means of notification for the user, which might be through the presence service, and transmits a notification to the user as to the unavailability of the application server. In the example embodiment, the process transmits a later notification as to the availability of the application server, using reverse camp-on functionality.

TECHNICAL FIELD

The present disclosure relates to the use of IP flow information andapplication service availability notification.

BACKGROUND

NetFlow is an open but proprietary network protocol developed by CiscoSystems for collecting Internet Protocol (IP) traffic information.NetFlow runs on equipment with Cisco Internetwork Operating System(IOS), but served as the basis for RFC 2778. Cisco routers that have theNetFlow feature enabled generate NetFlow records that are exported fromthe router in User Datagram Protocol (UDP) or Stream ControlTransmission Protocol (SCTP) packets and collected using a NetFlowcollector.

Network flows can be been defined in many ways, but a common definitionis as a 5-tuple, where a flow is defined as a unidirectional sequence ofpackets sharing the following values: (1) source IP address; (2)destination IP address; (3) source Transmission Control Protocol (TCP)port; (4) destination TCP port; and (5) IP protocol. The NetFlowprotocol uses this definition.

Typically, a router outputs a flow record when the router determinesthat the flow is finished through, for example, the use of flow aging.Or a TCP session termination in a TCP flow might cause the router toexpire the flow. Routers can also be configured to output a flow recordat a fixed interval even if the flow is still ongoing.

A NetFlow record can contain a wide variety of information about thetraffic in a given flow. For example, a Version 5 NetFlow recordcontains the following: (a) version number; (b) sequence number; (c)input and output interface for Simple Network Management Protocol (snmp)indices; (d) timestamps for the flow start and finish time; (e) numberof bytes and packets observed in the flow; (f) Layer 3 headers, whichinclude source and destination IP addresses, source and destination portnumbers, IP protocol, and ToS (Type of Service) value; and (g) in thecase of TCP flows, the union of all TCP flags observed over the life ofthe flow.

NetFlow records are usually sent via a UDP or SCTP in newer softwareand, for efficiency reasons, the router does not store NetFlow recordsonce they are exported. The IP address of the NetFlow collector and theport upon which it is listening must be configured on the sendingrouter. NetFlow is enabled on a per-interface basis in a router, whichallows the router to export NetFlow records for dropped packets.

In computer and telecommunications networks, presence information is astatus indicator that conveys ability and willingness of a potentialcommunication partner, such as a user, to communicate. Presenceinformation has been applied in different communication services, suchas instant messaging (IM) and voice over IP (VoIP).

Called-party camp-on is a service feature of a communication system thatenables the system to complete an access attempt in spite of issuance ofa blocking signal by a busy user. Systems that provide this featuremonitor the busy user until the blocking signal ends and then proceed tocomplete the requested access. In telecommunication systems, thisfeature permits holding an incoming call until the called party is free,hence the name “called-party camp-on”. This feature has recently beenextended to computer networks as reverse camp-on, where a busy serverinitiates a contact with an endpoint once the server is no longer busy.

DESCRIPTION OF THE DRAWINGS

For a complete understanding of the present invention and itsadvantages, reference is now made to the following description, taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a diagram showing a network topology, which topology might beused with some embodiments of the present invention.

FIG. 2 is a diagram showing an IP flow system, which system might beused with some embodiments of the present invention.

FIG. 3 is a diagram showing the hardware system for a router, whichrouter might be used with some embodiments of the present invention.

FIG. 4 is a diagram showing a flowchart of a user notification processusing IP flow, which process might be used with some embodiments of thepresent invention.

DESCRIPTION OF EXAMPLE EMBODIMENT(S)

In particular embodiments, the present invention provides methods,apparatuses, and systems directed to the use of IP flow information toidentify and selectively notify users as to the availability andunavailability of an application service hosted by a server. In oneparticular embodiment, the notification of the users employs presenceinformation maintained on a presence server and/or reverse camp-onfunctionality. The following example embodiments are described andillustrated in conjunction with apparatuses, methods, and systems whichare meant to be examples and illustrative, not limiting in scope.

A. Network Topology

FIG. 1 is a schematic diagram showing a network topology, which topologymight be used with some embodiments of the present invention. As shownin the diagram, two endpoints or client devices, a laptop 101 and a cellphone 102, are connected to a communication network 103, whichcommunication network might comprise a local area network (LAN), widearea network (WAN), global distributed network such as the Internet,Intranet, Extranet, or any other form of wireless or wire-linecommunication network. Also connected to communication network 103 arean IP flow system 105, comprising a router/switch, and a presence server104. The IP flow system 105 is also connected to an application server106, which might be running a web application, an electronic commerceapplication, a database application, or any other application whichreceives input from an endpoint and/or transmits output to an endpoint.Notification service 107 is operative to monitor for, or receive,indications of application service unavailability, and notify one ormore users of the application service unavailability. Notificationservice 107, in a particular implementation, is a computer-implementedprocess that may be hosted on any suitable device, such as a physicalserver, a router, switch or other network node.

In some embodiments, presence server 104 might be any combination ofhardware, software, and/or encoded logic and is used to detect andmonitor the presence of users at their endpoints. Presence server 104might include a single computer or a group of computers that are capableof detecting the presence of users at an endpoint. In some embodiments,an endpoint might include a presence client application running on theendpoint, such as an instant messaging client. The presence server 104may also be operative to provide availability or presence information ofsystem users to one or more client applications connected to thepresence server 104. Presence server 104 might detect that users arecommunicating on particular endpoints using a variety of communicationmethods. For example, presence server 104 might detect that a targetuser is currently communicating on his/her cell phone (e.g., cell phone102), IP phone, work phone, home phone, pager, PDA, PC or any othercommunication device such as laptop 101. In addition, presence server104 might detect that a user is currently communicating using aparticular communication method, such as e-mail, instant messaging (IM),or Short Message Service (SMS).

In a particular embodiment, communication network 103 employscommunication protocols that allow for the addressing or identificationof endpoints and nodes, which nodes might include servers 104 and 106,coupled to communication network 103. For example, using Internetprotocol (IP), each of the components coupled together by communicationnetwork 103 might be identified in information directed using IPaddresses. In this manner, communication network 103 might support anyform and/or combination of point-to-point, multicast, unicast, or othertechniques for exchanging media packets among components coupled to it.Any network components capable of exchanging audio, video, or otherdata, including presence information, instant messages and Short MessageService (SMS) messages, using frames or packet, are included within thescope of the present invention.

Communication network 103 might also be directly coupled to other IPnetworks including, but not limited to, a LAN or the Internet. Since IPnetworks share a common method of transmitting data, telecommunicationsignals might be transmitted between telephony devices located ondifferent, but interconnected, IP networks. In addition to being coupledto other IP networks, communication network 103 might also be coupled tonon-IP telecommunication networks through the use of interfaces orcomponents. It will be appreciated that IP networks transmit data(including voice and video data) by placing the data in packets andsending each packet individually to the selected destination, along oneor more communication paths. Unlike a circuit-switched network, adedicated circuit is not required for the duration of a call, IMsession, SMS session or fax transmission over IP networks.

In particular embodiments, communication network 103 and the componentscoupled to it might receive and transmit data in a session initiationprotocol (SIP) environment. SIP is an application-layer control protocolthat includes primitives for establishing, modifying, and terminatingcommunication sessions. SIP works independently of underlying transportprotocols and without dependency on the type of session that is beingestablished. SIP also transparently supports name mapping andredirection services, which, in turn, support personal mobility.

Still further, endpoints and/or client applications hosted on theendpoints, during connection initiation in enterprise networks,typically interact, and/or register, with a variety of systems, such asaccess points, controllers, switches, DHCP servers, authenticationservers, directory servers and presence servers. Some of these systemsmay include information that allows for a mapping between an endpoint IPaddress and a user name corresponding to the user of the endpoint. Thisuser name or other identity can then be used to identify one or morenotification channels for a user. For example, with a user name, anotification process can access a presence server 104, for example, todetermine whether an instant message or a VoIP call can be used as anotification method.

It will be recognized by those of ordinary skill in the art that inother embodiments, endpoints 101 and 102 might be any combination ofhardware, software, and/or encoded logic that provides communicationservices to a user and performs the functionality described herein. Forexample, in such embodiments, endpoints 101 and 102 might include atelephone, a computer running telephony software, a video monitor, acamera, an IP phone, a cell phone or any other communication hardware,software, and/or encoded logic that supports the communication ofpackets of media (or frames) using communication network 103. Endpoints101 and 102 might also include unattended or automated systems,gateways, other intermediate components, or other devices that canestablish media sessions.

B. IP Flow System

FIG. 2 is a diagram showing an IP flow system, which IP flow system 105might be used with some embodiments of the present invention. It will beappreciated that this IP flow system 105 might be used with the networktopology shown in FIG. 1, for example. As shown in FIG. 2, incoming IPtraffic is received by IP flow system 105, such as a router/switch(e.g., a Cisco® NetFlow router), which is a network forwarding devicethat gathers and stores information per flow. Once a flow expires, IPflow system 105 aggregates and filters the flow information andtransmits it to collector 202, which is connected to the IP flow system105 and which is depicted as a server in FIG. 2. Thereafter, thecollected flow information might optionally be transmitted further toworkstation 203, which runs an application program performing flowanalysis. In a particular embodiment, the process described below mightexecute in whole or in part as software/firmware/hardware (i.e., encodedlogic) on IP flow system 105, on collector 202, or on workstation 203.

A flow can be defined as a unidirectional or bidirectional sequence ofpackets with some common properties that pass through a network device.These collected flows are exported to an external device, such as aCisco® NetFlow collector. Network flows may be highly granular; forexample, flow records include details such as IP addresses, packet andbyte counts, timestamps, Type of Service (ToS), application ports, inputand output interfaces, TCP or other connection state information, andthe like. The collected information for a given flow may be transmittedin one or more packets as a flow record. A flow may be identified ordefined by a 5-tuple definition, where a flow may be defined as aunidirectional sequence of packets all sharing all of the following 5values: 1) Source IP address; 2) Destination IP address; 3) Source TCPport; 4) Destination TCP port; and 5) IP protocol.

An IP flow system, such as a router, may output a flow record when itdetermines that the flow is finished. In a particular implementation,the IP flow system may accomplish this by flow aging: when a router, forexample, sees new traffic for an existing flow it resets the agingcounter. Also, TCP session termination in a TCP flow causes the routerto expire the flow. Routers and other IP flow systems can also beconfigured to output a flow record at a fixed interval even if the flowis still ongoing.

A flow record can contain a wide variety of information about thetraffic in a given flow. Cisco® NetFlow version 5, for example, containsone or more of the following information elements: 1) Version number, 2)Sequence number, 3) Input and output interface Simple Network ManagementProtocol (SNMP) indices, 4) Timestamps for the flow start and finishtime, 5) Number of bytes and packets observed in the flow, and 6) Layer3 headers: Source & destination IP addresses, Source and destinationport numbers, IP protocol, and Type of Service (ToS) value. Furthermore,in the case of TCP flows, the union of all TCP flags observed over thelife of the flow can be included in the flow record. By analyzing flowdata, a picture of traffic flow and traffic volume in a network can bebuilt. In addition, the flow records can also be analyzed forindications of application service unavailability, and/or the identityof a notification channel for one or more active users of an applicationserver. For example, a set of flow records indicating that anapplication server 106 has not responded to connection initiationmessages (e.g., TCP SYN packets) may indicate that the applicationserver 106 is unavailable.

C. Hardware System for Router

FIG. 3 is a diagram showing the hardware system for a router, whichrouter might be used as an IP flow system 105 with some embodiments ofthe present invention. In one embodiment, the hardware system 300 shownin FIG. 3 includes a routing processor 310, system memory 312,persistent memory 318 (e.g., flash memory or a hard disk drive), arouting engine/switch fabric 304 connected to a plurality of ports 302,a system bus 308 interconnecting these components, and one more softwareor firmware modules (loadable into system memory 312) directed tonetwork routing functions (e.g., switch fabric and routing table/engineconfiguration, control message processing, BGP/IGP processing, NetFlowrecord generation, and the like). Other functional modules might includediscovery modules operative to discover the identity and capabilities ofneighboring network devices. In one embodiment, one or more of the ports302 might be Ethernet interfaces. The system architecture 300 mightoptionally include a console port 316 allowing for administrative accessfor purposes such as configuration and diagnostics.

D. User Notification Process Using IP Flow Information

FIG. 4 is a diagram showing a flowchart of a user notification processusing IP flow information, which process might be used with someembodiments of the present invention. It will be appreciated that theprocess might run in whole or in part in any component of the IP flowinformation collection system shown in FIG. 2. In a particularimplementation, IP flow system 105 may perform the process illustratedin FIG. 4. In other implementations, the notification processes may beperformed by a server process hosted on a separate physical server. Inthe first step 401 of the process shown in FIG. 4, the process obtainsinformation indicating that a connected application server (e.g., usinga last-mile connection) has or will become unavailable. In step 402, theprocess uses IP flow information collected by collector 202, forexample, to identify active users of the connected application server106 and, in step 403, determines a notification channel for one or moreactive users, which determination might involve contacting a presenceserver 104 for stored information about an active user. The process thentransmits a notification to the active user informing the user of theunavailability of the connected application server 106, in step 404.Finally, in step 405, the process optionally transmits a secondnotification to one or more of the active users, informing of theavailability of the connected application server (e.g., through the useof the reverse camp-on functionality described in commonly-owned U.S.Patent Application No. 2006/0245567 and U.S. Patent Application No.2006/0268698, whose disclosures are incorporated herein by reference forall purposes), when the connected application server 106 becomesavailable.

As described above, step 401 of the process obtains informationindicating that a connected application server has or will becomeunavailable. Such an indication might be proactive, insofar a systemadministrator might know that the connected application server 106 isgoing down soon due to scheduled maintenance, unscheduled overloading,etc. For example, a network administrator may transmit a message tonotification service 107 indicating that application server 106 isscheduled to be unavailable at a given point in the future. Moreover,the indication might not concern the connected application server 106itself, but might rather concern the connection to the connectedapplication server 106.

Further, in some embodiments, the IP flow system 105 might monitor theconnected application server 106 to obtain an indication ofunavailability or degraded performance, which degraded performance mightbe treated as a form of unavailability. As suggested above, IP flowrecords indicating dropped packets might be used for this purpose insome embodiments. For example, notification service 107 may process IPflow records maintained by collector 202 against a rule set to identifyindications of application service unavailability. In otherimplementations, if a predefined number of dropped packets destined forthe application server 106 occurs within a predefined period of time (asdetected by a router, such as IP flow system 105), then anunavailability notification process might be triggered. For example, afailure of application server 106 may cause IP flow system 105 to bufferone or more packets destined for the application server 106. Generally,packets are buffered for a threshold period of time and then dropped ordiscarded. A threshold number of such packet drops may indicateapplication service unavailability. In such an embodiment, IP flowsystem 105 may transmit one or more messages to, or otherwise invoke,notification service 107 to identify active uses of the applicationserver 106 and notify one or more active users. Other embodiments mightuse alternative, automated means for detecting application serviceunavailability, such as end-to-end (or E2E) monitoring.

As described above, step 402 of the process uses IP flow information toidentify active users of the connected application server 106. In someembodiments, such identification might make use of the source ordestination IP address which, as described earlier, is a field in an IPflow record. For example, the flow records that include the IP addressof the application server 106 may be identified. The identified flowrecords may be further filtered to identify only those flow recordswhere the time stamp is less than a threshold period of time from thecurrent time to identify the most recent flow records. The IP addressesof the client nodes or end points (such as 101 and 102) may beidentified by inspecting the source or destination IP address fielddepending on the direction of traffic flow corresponding to the flowrecords.

Notification service 107 may map the client IP addresses of the activeusers to other identifiers in order to select a notification channel. Apresence service (e.g., running on a presence server 104) can use theidentified client IP address to determine whether the IP address isassociated with a user of the service.

Alternatively, the IP flow system might use the client IP address to mapthe client IP address to a hostname. In the case of a static IP address,the IP flow system 105 might contact a server running the LightweightDirectory Access Protocol (LDAP) to do such mapping. In the case of adynamic IP address, the IP flow system 105 might contact a Dynamic HostConfiguration Protocol (DHCP) server to do such mapping. In either case,the mapping server, such as an LDAP server, with the hostname might alsobe able to provide an enterprise user identifier (ID) identifying theowner of the endpoint (e.g., laptop) associated with the hostname, whichenterprise user ID might then be used as an input into a presenceservice associated with the endpoint, or an alternative client endpointassociated with the enterprise user ID. Still further, one or more rulescan be applied to select a notification channel from a plurality ofcurrently available notification channels.

It will be appreciated that step 403 might be logically related to step402, insofar as the notification means might be dictated by the meansused to identify an active user. For example, if a presence service canmap a client IP address to a user of the application service hosted byapplication server 106, the presence service is an efficient means ofnotifying the user. However, another means of notification might be moreappropriate due, for example, to the time of day. Some embodiments mightchoose from alternative means of notification depending upon suchfactors. Further, in some embodiments, the content of the notificationmight be either customized or predefined/automated. Some embodimentsmight use the latter type of notification in conjunction with theunscheduled unavailability of the connected application server.

Additionally, the information contained in the notification transmittedto active users can vary based on the notification channel and/or one ormore attributes of the application service. For example, notificationservice 107 can use a default notification message. In otherimplementations, the notification service 107 may access a data set ofposted notification messages that are associated with either anidentified application service, server IP address, or port number andselect a message based on one or more attributes of the applicationservice. For example, if messages transmitted to the application serviceuse a well-known port number, notification service 107 may select anotification message associated with the well-known port number. Stillfurther, the notification service may select a notification messagebased on the notification channel. For example, short text notificationscan be used for IM or SMS messages, while longer messages can be usedfor email clients.

Particular embodiments of the above-described process might be comprisedof instructions that are stored on storage media. The instructions mightbe retrieved and executed by a processing system. The instructions areoperational when executed by the processing system to direct theprocessing system to operate in accord with the present invention. Someexamples of instructions are software, program code, firmware, andmicrocode. Some examples of storage media are memory devices, tape,disks, integrated circuits, and servers. The term “processing system”refers to a single processing device or a group of inter-operationalprocessing devices. Some examples of processing devices are integratedcircuits and logic circuitry. Those skilled in the art are familiar withinstructions, storage media, and processing systems.

Those skilled in the art will appreciate variations of theabove-described embodiments that fall within the scope of the invention.In this regard, it will be appreciated that there are many possibleorderings of the steps in the process described above and many possiblemodularizations of those orderings. As a result, the invention is notlimited to the specific examples and illustrations discussed above, butonly by the following claims and their equivalents.

1. A method, comprising: receiving an indication of unavailability of anapplication server; responsive to the indication of unavailability,accessing flow state information to identify one or more active users ofthe application server, wherein the flow state information includes datarelating to one or more data flows between the application server andone or more clients; determining a notification channel for one or moreof the active users; and transmitting a notification of unavailabilityof the application server to the one or more active users over therespective determined notification channels.
 2. The method of claim 1wherein the determining a notification channel comprises obtaining oneor more client IP addresses corresponding to one or more respectiveclients of the application server.
 3. The method of claim 2 wherein thedetermining a notification channel further comprises mapping the one ormore client IP addresses to respective user identifiers.
 4. The methodof claim 2 wherein the determining a notification channel furthercomprises providing one or more client IP addresses to a presenceservice to retrieve one or more respective user identifiers.
 5. Themethod of claim 2 wherein the determining a notification channel furthercomprises providing one or more client IP addresses to a DHCP server toretrieve one respective hosts names; and accessing, using the respectivehost names, a directory service to retrieve one or more useridentifiers.
 6. The method of claim 3 wherein the determining anotification channel further comprises accessing a presence serviceusing the one or more respective user identifiers.
 7. The method ofclaim 5 wherein the determining a notification channel further comprisesaccessing a presence service using the one or more respective useridentifiers.
 8. The method of claim 1 wherein the transmitting thenotification comprises selecting notification information based on oneor more attributes of the application server.
 9. The method of claim 1wherein the transmitting the notification comprises selectingnotification information based on one or more attributes of thenotification channel.
 10. The method of claim 1 further comprisingreceiving an indication of availability of the application server; andtransmitting a notification of availability of the application server tothe one or more active users using the respective determinednotification channels.
 11. The method of claim 1 wherein the indicationof unavailability of an application server is obtained by monitoring IPflow records for indications of dropped packets destined for theapplication server.
 12. The method of claim 1 wherein the indication ofunavailability of an application server is obtained from a routingsystem reporting one or more dropped packets destined for theapplication server.
 13. Logic encoded in one or more computer-readablemedia for execution and when executed operable to: receive an indicationof unavailability of an application server; responsive to the indicationof unavailability, access flow state information to identify one or moreactive users of the application server, wherein the flow stateinformation includes data relating to one or more data flows between theapplication server and one or more clients; determine a notificationchannel for one or more of the active users; and transmit a notificationof unavailability of the application server to the one or more activeusers over the respective determined notification channels.
 14. Thelogic of claim 13 wherein the logic is further operable to: obtain oneor more client IP addresses corresponding to one or more respectiveclients of the application server.
 15. The logic of claim 14 wherein thelogic is further operable to: map the one or more client IP addresses torespective user identifiers.
 16. The logic of claim 14 wherein the logicis further operable to: provide one or more client IP addresses to apresence service to retrieve one or more respective user identifiers.17. The logic of claim 14 wherein the logic is further operable to:provide one or more client IP addresses to a DHCP server to retrieve onerespective hosts names; and access, using the respective host names, adirectory service to retrieve one or more user identifiers.
 18. Themethod of claim 15 wherein the logic is further operable to: access apresence service using the one or more respective user identifiers. 19.The method of claim 17 wherein the logic is further operable to: accessa presence service using the one or more respective user identifiers.20. The logic of claim 13 wherein the logic is further operable to:select notification information based on one or more attributes of theapplication server.
 21. The logic of claim 13 wherein the logic isfurther operable to: select notification information based on one ormore attributes of the notification channel.
 22. The logic of claim 13wherein the logic is further operable to: receive an indication ofavailability of the application server; and transmit a notification ofavailability of the application server to the one or more active usersusing the respective determined notification channels.
 23. The logic ofclaim 13 wherein the indication of unavailability of an applicationserver is obtained by monitoring IP flow records for indications ofdropped packets destined for the application server.
 24. The logic ofclaim 13 wherein the indication of unavailability of an applicationserver is obtained from a routing system reporting one or more droppedpackets destined for the application server.
 25. An apparatuscomprising: one or more network interfaces; a memory; one or moreprocessors; and a notification process module comprising computerreadable instructions operative to cause the one or more processors to:receive an indication of unavailability of an application server;responsive to the indication of unavailability, access flow stateinformation to identify one or more active users of the applicationserver, wherein the flow state information includes data relating to oneor more data flows between the application server and one or moreclients; determine a notification channel for one or more of the activeusers; and transmit a notification of unavailability of the applicationserver to the one or more active users over the respective determinednotification channels.